He claims he's worried about her health conditions, but she knows better than that. The truth is that he's secretly thrilled at the prospect of having a nephew or niece, and that's the only reason why he agreed to help her with the shopping.
"Are you going to tell me who's the real father?" he demands, shooting a mildly perplexed look at the items of clothing she's inspecting.
Andrea smirks, then shakes her head. "I've already told you. Twice."
"I don't believe you," he scoffs, his brow furrowed in a vain attempt to delete the piece of information that his brain seems unable to process.
"You could always ask your brother," she shrugs, savouring the fleeting glimpse of panic that crosses his features.
"I can't see how my brother comes into this."
Oh, she loves it when he hands her the opportunity on a silver platter. "Do you really want me to explain all the details?" she teases him, and he flinches in alarm. "Or do you need me to start from the birds and the bees?"
"Mycroft gave me that one when I was twelve, thank you very much."
"And you actually listened to what he said?"
"I threw my science book at him, if I'm not mistaken," he points out somewhat proudly, and that's when she dissolves into laughter.